The present invention relates generally to a method and apparatus for connecting and disconnecting a supportive buoyant structure which is intended to transport and erect an offshore tower jacket alternately to and from the tower jacket. More particularly, the invention relates to an improved method and apparatus for rigidly connecting and locking together a supporative buoyant structure and an offshore tower jacket in such a way that the two structures can be positively connected to universally restrain relative movement of the structures and which can nonetheless be positively and reliably disconnected.
Specifically, the present invention constitutes improvements in relations to jacket handling techniques disclosed in United States Koehler et al U.S. Pat. No. 3,859,804 (Jan. 14, 1975) and Crout et al U.S. Pat. No. 3,823,564 (July 16, 1974), assigned to the assignee of the present invention. These improvements are designed to:
Enhance the ease and reliability with which jackets are detachably attached to buoyancy structures, PA1 Facilitate the selective release of such jackets and buoyancy structures, and PA1 Improve the reliability and ruggedness of connections maintained between such jackets and buoyancy structures as they are towed into position and the jacket is installed on a seabed.
In light of the foregoing, it is a general object of the invention to provide a novel method and apparatus intended to accomplish objectives of the type noted above.
It is a particular object of the invention to provide a novel method and apparatus by means of which a supportive buoyant structure can be rigidly locked in connection with an offshore tower jacket in a manner capable of resisting forces exerted as the jacket is turned upright and placed on the floor of the body of water.
It is another object of the invention to provide a method and apparatus by means of which a supportive buoyant structure can be positively connected to an offshore tower jacket and thereafter positively disconnected so that the supportive structure can be readily moved away from the jacket.
It is still another object of the invention to provide a novel method and apparatus capable of universally resisting movement of an offshore tower jacket aboard a supportive buoyant structure as a consequence of movement induced in the assembly by waves and wind.
It is yet still another object of the invention to provide an apparatus which is of sufficient strength to connect together a buoyant structure and an offshore tower jacket and resist loads incurred in the course of transporting and erecting the jacket.
It is a further object of the invention to provide a novel method and apparatus for connecting together a supportive buoyant structure and an offshore tower jacket in a highly reliable manner.
It is still a further object of the invention to provide a novel method and apparatus for connecting together an offshore tower jacket and a supportive buoyant structure in which the apparatus employed to effect the connection is reusable over essentially the same number of cycles as the supportive buoyant structure.
It is yet still a further object of the invention to provide a novel method and apparatus which connects an offshore tower jacket to a supportive buoyant structure in a manner such that the jacket is maintained in a position above the surface of the body of water to avoid undue hydrodynamic resistance to the movement of the assembly to a desired offshore location.
It is another object of the invention to provide a novel method and apparatus for connecting together an offshore tower jacket and a supportive buoyant structure in which the apparatus employed is safe to use and work around as the jacket is being constructed, transported, and erected at a desired offshore location.
An apparatus for connecting and disconnecting a supportive buoyant structure, intended to transport and erect an offshore tower jacket, alternately to or from the tower jacket and intended to meet the foregoing objectives involves a clamping means which is carried in a reciprocally movable relation by the buoyant structure. The clamping means rigidly but releasably clamps together the tower jacket and the buoyant structure. The apparatus further involves elongated, structural linking means which reciprocally moves the clamping means relative to the buoyant structure. The linking means is pivotally connected at one end to the clamping means. Bellcranking means serves to reciprocally move the linking means and as a consequence moves the clamping means alternately into or out of clamping relation with the tower jacket and the supportive buoyant structure to positively connect or disconnect the two structures. The bellcranking means is pivotally connected to the buoyant structure for rotation about an axis which is normally horizontal. Rotating means connected to the bellcranking means serves to rotate the bellcranking means in order to reciprocally move the linking means and the clamping means relative to the buoyant structure.
A method of connecting and disconnecting a supportive buoyant structure intended to transport and erect an offshore tower jacket alternately to or from the tower jacket and intended to meet the foregoing objectives entails a number of steps. The first of these involves axially mating opposed stanchions extending vertically between the buoyant structure and the tower jacket. The mating surfaces of the stanchions are clamped together and thereafter positively locked in this clamped relation prior to transporting the tower jacket and the buoyant structure to an offshore location. Once the desired offshore location is reached, the mating surfaces are positively unlocked and thereafter released from the previous clamped relation.